Hybrid ball stud

ABSTRACT

The present invention provides a ball joint for use in interconnecting a pair of components to accommodate relative angular movement therebetween. The ball joint includes a socket assembly and a hybrid ball stud. The socket assembly includes a cup-shaped housing defining a cavity therein and an insert disposed within the housing cavity and which defines a spherical ball socket. The hybrid ball stud includes a standard bolt and a polymeric insert attached to, or encapsulating, the head of the bolt to define a spherical ball or a partial spherical ball. The polymeric insert is adapted to be retained in the ball socket. The bolt is a high-volume commercially-available component having a threaded shank segment and a head segment which is over-molded or fitted with the polymeric insert. As such, an inexpensive hybrid ball stud is provided for use in ball joints.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to ball joints and, moreparticularly, to a hybrid ball stud for a ball joint comprised of a boltand a spherical polymeric component secured to the head of the bolt todefine a ball segment of the ball stud.

[0003] 2. Discussion

[0004] As is known, motor vehicles are equipped with suspension systemsfor absorbing road shock and other vibrations while providing a smoothand comfortable ride for the vehicle occupants. In virtually allvehicular suspension systems, ball joints are used to interconnectsuspension components for accommodating changes in angularitytherebetween. In general, most conventional ball joints include a ballstud, a ball socket, and a housing. Typically, the ball stud is a forgedmetallic component having an elongated shank segment and a ball segment.The shank segment of the ball stud is connected to one suspensioncomponent and the housing is fixed to the other suspension component.The ball segment of the ball stud is retained in a spherical cavityformed in the ball socket which, in turn, is mounted in the housing. Tofacilitate angular movement of the ball stud relative to the housing,the sphericity and surface profiles of the ball segment must be highlyprecise. These component characteristics have conventionally requiredthe utilization of expensive and time-consuming secondary machining andfinishing operations.

[0005] As an alternative to forged ball studs, it is known to provide aball joint equipped with a ball stud having a polymeric layer moldedover the ball segment. See, for instance, U.S. Pat. Nos. 2,862,740,2,905,492 and 3,091,486. As a further alternative, some ball studs havea polymeric ball mounted to one end of a threaded stud. See, forexample, U.S. Pat. Nos. 2,999,709, 3,023,038, 3,941,495 and 5,697,142.Finally, it is also known to surround a portion of a threaded stud witha partially spherical polymeric insert and which engages a radial flangeextending from the stud. See, for example, U.S. Pat. No. 2,823,055,2,846,252, 2,937,895, 2,953,401, 3,091,486, 4,334,795 and 4,629,352. Ineach case, a molded component is used as the ball segment to limit oreliminate the secondary surface finishing operations associated withconventional forged ball studs.

[0006] Although various composite assemblies have been proposed forconstructing a ball stud to avoid the machining and heat treatingrequirements associated with forged ball studs, none have beensuccessful in significantly reducing production costs. Therefore, itwould be desirable to provide a ball joint having a composite ball studrequiring minimal labor and processing costs.

SUMMARY OF THE INVENTION

[0007] The present invention provides a ball joint for use ininterconnecting a pair of components to accommodate relative angularmovement therebetween. The ball joint includes a socket assembly and ahybrid ball stud. The socket assembly includes a cup-shaped housingdefining a cavity therein and an insert disposed within the housingcavity and which defines a spherical ball socket. The hybrid ball studincludes a standard bolt and a polymeric insert attached to, orencapsulating, the head of the bolt to define a spherical ball or apartial spherical ball. The polymeric insert is adapted to be retainedin the ball socket. The bolt is a high-volume commercially-availablecomponent having a threaded shank segment and a head segment which isover-molded or fitted with the polymeric insert. As such, an inexpensivehybrid ball stud is provided for use in ball joints.

[0008] As a further feature of the present invention, a partiallyspherical polymeric member may be molded on, or attached to, the shanksegment of the bolt such that the polymeric member and the sphericalhead segment of the bolt combine to serve as the ball segment of theball stud.

[0009] According to another feature of the present invention, a toroidalpolymeric member is molded on, or attached to, the head of the bolt toserve as the ball segment of the ball stud.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to appreciate the manner in which the advantages andobjects of the invention are obtained, a more particular description ofthe invention will be rendered by reference to specific embodimentsthereof which are illustrated in the appended drawings. Understandingthat these drawings only depict preferred embodiments of the presentinvention and are not therefore to be considered limiting in scope, theinvention will be described and explained with additional specificityand detail through the use of the accompanying drawings in which:

[0011]FIG. 1 is a sectional view of a ball and socket assembly equippedwith a hybrid ball stud made in accordance with one preferred embodimentof the present invention;

[0012]FIG. 2 is a side elevational view of the hybrid ball stud shown inFIG. 1;

[0013]FIG. 3 is a side elevational view of a hybrid ball stud made inaccordance with another embodiment of the present invention;

[0014]FIG. 4 is a sectional view of the hybrid ball stud of FIG. 3;

[0015]FIG. 5 is a side elevational view of a hybrid ball stud made inaccordance with yet another embodiment of the present invention;

[0016]FIG. 6 is a sectional view of the ball stud of FIG. 5;

[0017]FIGS. 7 and 8 are side elevational views of additional alternativeembodiments for the hybrid ball stud of the present invention;

[0018]FIG. 9 is a side elevational view of another embodiment of thepresent invention;

[0019]FIG. 10 is a sectional view of the hybrid ball stud shown in FIG.9; and

[0020]FIGS. 11 through 14 illustrates further alternative embodiments ofthe hybrid ball stud of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In general, the present invention is directed toward a ball jointfor accommodating relative angular movement between a pair of suspensioncomponents such as, for example, a stabilizer bar and a control arm in avehicle suspension. The ball and socket assembly of the presentinvention includes a hybrid ball stud adapted to replace mostconventional ball studs and to work in conjunction with ball joints toprovide reduced cost without impairing performance of the vehiclesuspension. Thus, the ball joint of the present invention may beutilized with a wide variety of systems and is not intended to belimited to the particular application described herein.

[0022] Referring initially to FIG. 1, a ball and socket assembly,hereinafter referred to as ball joint 10, is shown to be of the typeadapted to interconnect a pair of suspension members and accommodaterelative angular motion therebetween. In general, ball joint 10 includesa hybrid ball stud 12 and a socket assembly 14. Socket assembly 14 isshown to include a housing 16, an end cap 18 enclosing one end ofhousing 16, and a polymeric liner 20 retained in an open-ended cavity 22of housing 16. Liner 20 is formed to include a spherical socket 24.

[0023] Hybrid ball stud 12 includes a bolt 26 having a shank segment 28on which external threads 30 are formed and a head segment 32. As willbe detailed, bolt 26 is a standard “off-the-shelf” component commonlyreferred to as a round head bolt. As such, head segment 32 of bolt 26 ishemispherical and defines an outer surface 34 that is adapted to engagethe inner wall surface of socket 24 in liner 20. Hybrid ball stud 12 isfurther shown to include a hemispherical component 36 that is made of asuitable polymeric material. Hemispherical component, hereinafterreferred to as polymeric insert 36, has an aperture defining an innersurface 37 which surrounds a proximal end portion of shank segment 28adjacent to head segment 32 such that its planar top surface 38 isjuxtapositioned adjacent to a planar underside surface 40 of headsegment 32. Polymeric insert 36 has an outer surface 42 adapted toengage the inner surface of socket 24 in liner 20. Preferably, theradius of polymeric insert 36 is identical to that of head segment 32 soas to cooperatively define a spherical ball 44 which is retained insocket 24 for angular movement relative to housing 16 and liner 20.

[0024] Referring again to FIG. 1, ball joint 10 is shown interconnectingtwo relatively movable components. In particular, an arm segment 46 of astabilizer bar 48 is shown to have shank segment 28 of bolt 26 extendingthrough a bore 50 formed therein. A nut 52 is threaded onto shanksegment 28 and acts as a stop flange which is positioned against aplanar face surface 54 of arm segment 46. With threaded shank segment 28extending through bore 50, a lock nut 56 is tightened onto threads 30and into engagement with an opposite planar face surface 58 of armsegment 46. Accordingly, bolt 26 of ball joint 10 is secured tostabilizer bar 48. In addition, housing 16 is fixed to a rod or link 60which is suitably fixed to another suspension component or a framecomponent of the motor vehicle. If ball joint 10 is part of an end link,then a second ball joint is attached to the opposite end of link 60 and,in turn, its bolt is secured to a control arm. Those skilled in this artwill appreciate that this particular arrangement is merely exemplary ofbut one of the many applications to which ball joint 10 can be employed.

[0025] Polymeric insert 36 can be molded insitu to surround the proximalend of shank segment 28 of bolt 26. In the alternative, insert 36 may bepreformed and include a through bore that is slid over the distal end ofshank segment 28 with surface 37 then being adhesively bonded to theproximal end of shank segment 28 and/or surface 38 being adhesivelybonded to underside surface 40 of head segment 32. In either case,hybrid ball stud 12 is fabricated or assembled using a standardround-head bolt 26.

[0026] As a further alternative, FIGS. 3 and 4 illustrate a ball stud 12a adapted for use in ball joint 10 and having a segmented polymericinsert 36 a mounted to round-head bolt 26. In particular, segmentedpolymeric insert 36 a is identical to insert 36 except that is has beencut into sections 62. In this application, sections 62 are preformed andthen adhesively bonded to one another along section lines 64, and/orbonded to bolt 26 along mating radial surfaces 38 a and 40 as well asalong the proximal portion of shank segment 28. Outer surface 42 a ofinsert sections 62 are spherical such that insert 36 a and head segment32 define spherical ball 44 a. Preferably, insert 36 a consists of twoquadrant sections 62, however any number of sections is contemplated.

[0027] Referring now to FIGS. 5 and 6, a ball stud 12 b for use in balljoint 10 is shown to have a polymeric ball insert 36 b secured to around-head square-neck bolt 26 b. Bolt 26 b is similar to bolt 26 exceptthat shank segment 28 includes a four-sided neck flange 70 adjacent tounderside surface 40 of round-head segment 32. Those components orfeatures of ball stud 12 b that are similar to those previouslydisclosed are identified by common reference numbers. Neck flange 70serves as an anti-rotation feature which assists in preventing rotationof ball insert 36 b relative to shank segment 28. As previouslydisclosed, insert 36 b can be molded insitu or, in the alternative, be apreformed as a unitary component or as a series of sections which areadhesively secured to bolt 26 b to cooperate with head segment 32 todefine a spherical ball 44 b. Again, a standard round-head square-neckbolt 26 b is used to fabricate or assemble ball stud 12 b. As a furtheroption, any other standard bolt configurations having a non-square neckflange (i.e., hexagonal) can be substituted for bolt 26 b.

[0028] Referring now to FIG. 7, a ball stud 12 c for use in ball joint10 is partially shown to include a polymeric insert 36 c secured to around-head bolt 26 c having ribs or serrations 72 formed on the proximalend of shank segment 28 in adjacent to head segment 32. Serrations 72assist in preventing rotation of insert 36 c relative to head segment 32of bolt 26 c. Insert 36 c can be molded insitu or can be preformed as aunitary component, or a series of preformed sections, adhesively bondedto mating surfaces on bolt 26 c.

[0029]FIG. 8 partially illustrates a ball stud 12 d for use in balljoint 10 including a polymeric insert 36 d secured to a head segment 74and a shank segment 76 of a T-head bolt 78. Head segment 74 has anarcuate portion 80 integrated with a rectangular hub 82. Insert 36 d isformed such that the radius of its outer surface 42 matches and iscontiguous with outer surface 84 of head segment 74.

[0030] Referring now to FIGS. 9 and 10, a ball stud 12 e for use in balljoint 10 is disclosed as having a polymeric insert 86 molded over an endportion of a standard hexagon head bolt 88. In particular, bolt 88 has ashank segment 90 and a hex-shaped head segment 92. Head segment 92 and aportion of shank segment 90 are encapsulated by insert 86. As istypical, shank segment 90 has external threads 94. As an alternative,insert 86 can be segmented into distinct section, such as optionallyindicated by joint line 96 (in phantom), and adhesively bonded to bolt88. Hex-shaped head segment 92 functions to prevent rotation of insert86 relative to bolt 88. While polymeric insert 86 is shown to bespherical, it is to be understood that insert 86 can have any geometricshape provided with an outer surface adapted to matingly engage at leasta portion of the ball joint socket for facilitating angular motiontherebetween.

[0031]FIG. 11 illustrates a ball stud 12 f which is similar to balljoint 12 e except that spherical polymeric insert 86 f is segmented intosections 98 a and 98 b with a snap-lock type connection provided alongjoint line 100. In particular, sets of lugs 102 are formed on section 98a and are adapted for receipt in sockets 104 formed in section 98 b todefine spherical ball 86 f. In addition, circular grooves 106 are formedin outer surface 108 of ball 86 f, either transversely or parallel toshank segment 90 of bolt 88 to permit lubricating grease to be packedtherein.

[0032]FIG. 12 illustrates a hybrid ball stud 12 g which is generallysimilar to ball stud 12 e of FIGS. 9 and 10 except that sphericalpolymeric insert 110 includes a recessed portion 112 defining an opening114 and a circumferential cantilevered spring flange 116. This resilientspring flange arrangement functions to spring load ball stud 12 g insocket 24 of ball joint 10.

[0033]FIG. 13 illustrates another hybrid ball stud 12 h having an insert120 molded on, or affixed to, head segment 92 of hexagon bolt 88. Insert120 includes a body portion 122 and a hemispherical nobbin portion 124.Nobbin is adapted for retention in a partially spherical spring seatformed in the ball socket while an outer surface 126 of body portion 122is adapted to be retained in a modified socket 24 of liner 20.

[0034]FIG. 14 illustrates another hybrid ball stud 12 i having atoroidal polymeric insert 130 molded on, or affixed to, head segment 92of hexagon bolt 88. Insert 130 is doughnut-shaped and has an outersurface 132 adapted to engage the inner surface of socket 24 in liner 20of ball joint 10.

[0035] Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention hasbeen described in connection with particular examples thereof, the truescope of the invention should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, specification, and following claims.

What is claimed is:
 1. A ball joint comprising: a socket assemblydefining a spherical ball socket; and a hybrid ball stud including abolt having a head segment and a shank segment, and a polymeric insertcooperating with said head segment to define a spherical ball retainedin said ball socket.
 2. The ball joint of claim 1 wherein said headsegment of said bolt is partially spherical to define an outer surfaceadapted to engage a complementary inner surface of said ball socket. 3.The ball joint of claim 2 wherein said polymeric insert is partiallyspherical and defines an outer surface adapted to cooperate with saidouter surface of said partially spherical head segment of said bolt toengage said inner surface of said ball socket.
 4. The ball joint ofclaim 3 wherein said polymeric insert has an aperture defining an innersurface which surrounds a proximal portion of said shank segmentadjacent to said head segment.
 5. The ball joint of claim 4 wherein saidpolymeric insert has a top surface juxtapositioned adjacent to anunderside surface of said head segment.
 6. The ball joint of claim 3wherein said polymeric insert is bonded to said bolt to define saidspherical ball.
 7. The ball joint of claim 2 wherein said bolt is around head bolt and said polymeric insert is bonded below said headsegment of said bolt.
 8. The ball joint of claim 7 wherein saidpolymeric insert includes a plurality of insert segments surrounding aportion of said shank segment of said bolt to cooperatively define aspherical outer surface.
 9. The ball joint of claim 2 wherein said shanksegment includes a multi-sided neck flange adjacent an underside surfaceof said head segment, and said polymeric insert encapsulates said neckflange.
 10. The ball joint of claim 2 wherein said shank segmentincludes serrations or ribs adjacent to said head segment and saidpolymeric insert encapsulates said serrations or ribs.
 11. The balljoint of claim 1 wherein said bolt is a T-head bolt and said headsegment includes a hub portion mounted to said shank segment and anarcuate portion engaging said ball socket.
 12. The ball joint of claim 1wherein said polymeric insert is a ball and said bolt has a hex-shapedhead segment encapsulated in said ball.
 13. The ball joint of claim 12wherein said polymeric insert includes a pair of hemispherical sectionsinterconnected to define said ball.
 14. The ball joint of claim 13wherein one of said segments includes lugs and the other of saidsegments includes sockets sized to receive said lugs to define asnap-lock arrangement.
 15. A ball joint comprising: a housing defining acavity; a liner retained in said cavity and defining a spherical ballsocket; and a hybrid ball stud including a bolt having a head segmentand a shank segment, said head segment is partially spherical to definean outer surface engaging an inner surface of said ball socket and saidpolymeric insert is partially spherical to define an outer surfaceengaging said inner surface of said ball socket.
 16. The ball joint ofclaim 15 wherein said polymeric insert has an aperture defining an innersurface which surrounds a proximal portion of said shank segment, and atop surface juxtapositioned adjacent to an underside surface of saidhead segment.
 17. The ball joint of claim 15 wherein said polymericinsert is bonded to said bolt to define a spherical ball in conjunctionwith said head segment.
 18. The ball joint of claim 15 wherein saidpolymeric insert is a plurality of insert segments surrounding a portionof said shank segment of said bolt to cooperatively define a sphericalouter surface.
 19. The ball joint of claim 15 wherein said shank segmentincludes a multi-sided neck flange adjacent an underside surface of saidhead segment, and wherein said polymeric insert encapsulates said neckflange.
 20. A hybrid ball stud for use in a ball joint, comprising: abolt having a shank segment and a head segment; and an at leastpartially spherical polymeric insert cooperating with said head segmentof said bolt for defining a ball segment.
 21. The ball stud of claim 20wherein said bolt is a round-head bolt having a partially spherical headsegment, and wherein said insert is disposed adjacent said head segmentsuch that an outer surface of said head segment and an outer surface ofsaid insert combine to form a spherical outer surface of said ballsegment.
 22. The ball stud of claim 20 wherein said insert is aplurality of complementary insert segments which cooperate to definesaid ball segment.
 23. The ball stud of claim 22 wherein said insertsegments are snap fit together to surround said shank segment of saidbolt.
 24. The ball stud of claim 20 wherein said insert is molded oversaid head segment of said bolt.
 25. The ball stud of claim 20 whereinsaid polymeric insert further comprises a recessed portion and a flangeextending over said recessed portion to define a resilient springmember.
 26. A suspension system for a motor vehicle comprising: a firstsuspension member; a second suspension member; and a ball jointinterconnecting said first and second suspension members, said balljoint including a socket assembly fixed to said first suspension memberand defining a spherical ball socket, said ball joint further includinga hybrid ball stud comprised of a bolt having a head segment and a shanksegment fixed to said second suspension member, and a polymeric insertcooperating with said head segment to define an at least partiallyspherical ball segment retained in said ball socket.
 27. The suspensionsystem of claim 26 wherein said head segment of said bolt is partiallyspherical to define an outer surface adapted to engage a complementaryinner surface of said ball socket.
 28. The suspension system of claim 26wherein said bolt is a round head bolt and said polymeric insert isbonded below said head segment of said bolt.
 29. The suspension systemof claim 26 wherein said polymeric insert includes a plurality of insertsegments surrounding a portion of said shank segment of said bolt tocooperatively define a spherical outer surface.
 30. The suspensionsystem of claim 26 wherein said polymeric insert includes a pair ofhemispherical sections interconnected to define said ball.
 31. Thesuspension system of claim 30 wherein one of said segments includes lugsand the other of said segments includes sockets sized to receive saidlugs to define a snap-lock arrangement.
 32. The suspension system ofclaim 26 wherein said polymeric insert further comprises a recessedportion and a flange extending over said recessed portion to define aresilient spring member.
 33. A ball joint comprising: a socket assemblydefining a socket; and a hybrid ball stud including a bolt having a headsegment and a shank segment, and a toroidal polymeric insert secured tosaid head segment and which is retained in said socket.